Description Steller's sea cow

the skull of steller s sea cow, natural history museum of london

steller s sea cows grew 8 9 m (26 30 ft) long adults, larger extant sirenians. georg steller s writings contain 2 contradictory estimates of weight: 4 , 24.3 metric tons (4.4 , 26.8 short tons). true value estimated fall between these figures, @ 8–10 metric tons (8.8–11.0 short tons). size made sea cow 1 of largest mammals of holocene epoch, aside whales. sea cow s large size adaptation reduce surface-area-to-volume ratio , conserve heat. unlike other sirenians, steller s sea cow positively buoyant, meaning unable submerge. had thick outer skin, 2.5 centimeters (1 in), prevent injury sharp rocks , ice, , possibly prevent unsubmerged skin drying out. sea cow s blubber 8–10 centimeters (3–4 in) thick, adaptation frigid climate of bering sea lived. skin brownish-black, white patches on individuals. smooth along , rough on sides, crater-like depressions caused parasites. rough texture led animal being nicknamed bark animal . hair on body sparse, insides of sea cow s flippers covered in bristles. forelimbs 67 centimeters (26 in) long, , tail fluke forked.

the sea cow s head small , short in comparison huge body. animal s upper lip large , broad, extending far beyond lower jaw mouth appeared located underneath skull. unlike other sirenians, steller s sea cow toothless , instead had dense array of interlacing white bristles on upper lip. bristles approximately 3.8 centimeters (1.5 in) in length , used tear seaweed stalks , hold food. sea cow had 2 keratinous plates located on palate , mandible used chewing. according steller, these plates (or masticatory pads ) held interdental papillae, part of gums, , had many small holes containing nerves , arteries.

model in natural history museum of london

as sirenians, sea cow s snout pointed downwards, allowed better grasp kelp. sea cow s nostrils 5 centimeters (2 in) long , wide. in addition within mouth, sea cow had stiff, 10–12.7 centimeters (3.9–5.0 in) long bristles protruding muzzle. steller s sea cow had small eyes located halfway between nostrils , ears black irises, livid eyeballs, , canthi not externally visible. animal had no eyelashes, other diving creatures such sea otters, steller s sea cow had nictitating membrane covered eyes prevent injury while feeding. tongue small , remained in of mouth, unable reach masticatory (chewing) pads.

the sea cow s spine believed have had 7 cervical (neck), 17 thoracic, 3 lumbar, , 34 caudal (tail) vertebrae. ribs large, 5 of 17 pairs making contact sternum; sea cow had no clavicles. in sirenians, scapula of steller s sea cow fan-shaped, being larger on posterior side , narrower towards neck. anterior border of scapula straight, whereas of modern sirenians curved. other sirenians, bones of steller s sea cow pachyosteosclerotic, meaning both bulky (pachyostotic) , dense (osteosclerotic). in collected skeletons of sea cow, manus missing; since dusisiren—the sister taxon of hydrodamalis—had reduced phalanges (finger bones), possible steller s sea cow did not have manus @ all.

the sea cow s heart 16 kilograms (35 lb) in weight; stomach measured 1.8 metres (6 ft) long , 1.5 metres (5 ft) wide. full length of intestinal tract 151 metres (500 ft) long, equaling more 20 times animal s length. sea cow had no gallbladder, did have wide common bile duct. anus 10 centimeters (0.33 ft) in width, feces resembling of horses. male s penis 80 centimeters (2.6 ft) long.